Our earlier work showed that the laboratory diagnosis of Pneumocystis pneumonia could be done reliably with bronchoalveolar lavage (BAL) specimens and often as well with induced sputa, particularly in conjunction with a fluorescent monoclonal antibody stain. In addition, we reported that Pneumocystis polymerase chain reaction (PCR) can increase the sensitivity of detection when testing induced sputa. More recent work from Denmark suggests that PCR can successfully detect Pneumocystis even from simple oral washes. The use of oral washes would greatly benefit patients, since sputum induction is often difficult and unpleasant. We have started a prospective study to look at the comparative sensitivity of induced sputa and oral washes to detect Pneumocystis. For this study, every patient scheduled to undergo sputum induction will simultaneously submit an oral wash specimen by gargling first with a salt solution. Both specimens will be stained using our fluorescent monoclonal antibody procedure. All specimens will then be tested, in a blinded fashion, by PCR assay. Patients who are negative by induced sputum screening will generally also have BAL performed when clinically indicated, which will be used to confirm fluorescent antibody and PCR negative induced sputa and oral washes.